EFFECT OF LITHODYNAMIC FACTORS ON NOBLE-M ETAL DISTRIBUTION IN PARTICULATE MATTER AND BOTTOM SEDIMENTS IN THE MARINE PART OF THE ANADYR ESTUARY

Neutron activation analysis was used to determine the contents and stu dy the distribution of Ru, Ag, Os, Ir, Pt, and Au in particulate matte r (PM) and bottom sediments in the marine part of the Anadyr estuary. As terrigenous material passes through the mixing zone of fluvial and marine waters, it is depleted in all noble metals (NM) except Ir. The NM enrichment of seawater PM depends on the content of the fine-graine d fraction and biogenic material. In addition to these factors, the NM distribution in the bottom sediments is influenced by the possible pr esence of native Au, Pt, and Ag. The low NM abundances in the bottom s ediments relative to sedimentary rocks can be due to the deposition of heavy minerals in the Anadyr lagoon and to the dilution of fine-grain ed terrigenous material by amorphous silica of biogenic origin.